Arc extinguish chamber and isolating switch

Abstract

The utility model provides an arc extinguish chamber and an isolating switch, and relates to the low-voltage electrical field. The utility model provides an arc extinguish chamber which comprises a shell and a permanent magnet, the shell is made of a gas production material, a containing cavity is formed in the middle of the shell, the permanent magnet is arranged in the containing cavity, and a preset included angle alpha is formed between the arrangement direction of the permanent magnet and the extension direction of the shell; when a plurality of permanent magnets are arranged, the like polarity ends of the plurality of permanent magnets are arranged in the same direction. According to the arc extinguishing chamber obtained through the arrangement, the electric arc is subjected to the magnetic blowing effect of the permanent magnet and the air blowing effect of the shell at the same time, the electric arc can disappear rapidly while the low cost is kept, and the arc extinguishing efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the field of low-voltage electrical equipment, and in particular to an arc extinguishing chamber and an isolating switch. Background Art

[0002] When a general isolating switch is in use, an arc will be generated when the moving contact arm is separated from the static contact. Especially in the case of overload and short circuit, the huge current in the circuit will cause an arc to burn between the disconnected moving and static contacts. If the arc cannot be extinguished quickly to cut off the circuit, the isolating switch itself and the protected electrical equipment will all burn out and cause a fire, resulting in huge losses and thus causing safety problems. Therefore, the arc extinguishing mechanism should try to make the arc disappear quickly while maintaining low cost. Utility Model Content

[0003] The utility model aims to provide an arc extinguishing chamber and an isolating switch, which can make the arc disappear quickly while keeping low cost, thereby improving the arc extinguishing efficiency.

[0004] The embodiment of the utility model is achieved as follows:

[0005] In one aspect of the utility model, an arc extinguishing chamber is provided, comprising a shell and a permanent magnet. The shell is made of a gas-generating material. A receiving cavity is provided in the middle of the shell. The permanent magnet is arranged in the receiving cavity. The arrangement direction of the permanent magnet forms a preset angle α with the extension direction of the shell. When the permanent magnet comprises multiple permanent magnets, the same polarity ends of the multiple permanent magnets are arranged in the same direction.

[0006] Optionally, when there are multiple permanent magnets, the central axes of two adjacent permanent magnets along the thickness direction form a preset angle β, so that the multiple permanent magnets are arranged in an arc shape; wherein the thickness direction is perpendicular to the setting direction of the permanent magnets.

[0007] Optionally, the angle α is between 3° and 20°.

[0008] Optionally, the angle β is set at 10° to 30°.

[0009] Optionally, the shell includes two mounting parts, a slot is provided in the middle of the mounting parts, and the two mounting parts are connected so that the two slots are connected to form a containing cavity; the permanent magnet is arranged through the slots of the two mounting parts.

[0010] Optionally, a first plate surface extends from the end surfaces of the two mounting members facing away from each other, the first plate surface is perpendicular to the plane where the permanent magnet extends, and a second plate surface is bent at one end of the first plate surface away from the mounting member, and the first plate surface and the second plate surface form an arc track.

[0011] Optionally, a protruding portion and a clamping portion are respectively provided on the sides of the two mounting parts close to each other, and the protruding portion is structurally adapted to the clamping portion, and the protruding portion can be clamped with the clamping portion.

[0012] Optionally, the edge of the end surface where the N pole or S pole of the permanent magnet is located is provided with a chamfered structure.

[0013] Another aspect of the utility model provides an isolating switch, including a base and an arc extinguishing chamber. The base is provided with a contact mechanism, the contact mechanism includes relatively arranged static contacts and a moving contact movably cooperated with the static contacts, and arc extinguishing chambers are respectively arranged on opposite sides of the contact mechanism. The permanent magnet in the arc extinguishing chamber passes through the plane to which the moving contact and the static contact belong when they are in electrical contact.

[0014] Optionally, the permanent magnets respectively arranged in two oppositely arranged arc extinguishing chambers are parallel to each other; or, the permanent magnets respectively arranged in two oppositely arranged arc extinguishing chambers are symmetrically arranged with the contact mechanism as the symmetry axis, and the ends close to the moving contact are close to each other; or, the permanent magnets respectively arranged in two oppositely arranged arc extinguishing chambers are symmetrically arranged with the contact mechanism as the symmetry axis, and the ends close to the moving contact are far away from each other.

[0015] The beneficial effects of the utility model include:

[0016] The present application provides an arc extinguishing chamber, including a shell and a permanent magnet, wherein the shell is a gas-generating material, the middle part of the shell has a receiving cavity, the permanent magnet is arranged in the receiving cavity, and the arrangement direction of the permanent magnet forms a preset angle α with the extension direction of the shell; when the permanent magnet includes multiple permanent magnets, the same polarity ends of the multiple permanent magnets are arranged in the same direction. The arc extinguishing chamber obtained by the above arrangement allows the arc to be simultaneously subjected to the magnetic blowing effect of the permanent magnet and the gas blowing effect of the shell, which can make the arc disappear quickly while maintaining low cost, thereby improving the arc extinguishing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the structure of the arc extinguishing chamber provided in an embodiment of the utility model;

[0019] Figure 2 One of the structural schematic diagrams of the mounting member provided in the embodiment of the utility model;

[0020] Figure 3 The second structural schematic diagram of the mounting member provided in the embodiment of the utility model;

[0021] Figure 4 One of the structural schematic diagrams of the installation piece and the permanent magnet assembly provided in the embodiment of the utility model;

[0022] Figure 5 The second structural schematic diagram of the installation member and the permanent magnet assembly provided in the embodiment of the utility model;

[0023] Figure 6 A schematic diagram of the structure of a permanent magnet provided in an embodiment of the utility model;

[0024] Figure 7 A cross-sectional view of the assembly of the mounting member and the permanent magnet provided in the embodiment of the utility model;

[0025] Figure 8 A schematic diagram of the structure of the isolating switch provided in an embodiment of the utility model;

[0026] Fig. 9 One of the cross-sectional views of the isolating switch provided in the embodiment of the utility model;

[0027] Fig.10 The second cross-sectional view of the isolating switch provided in the embodiment of the utility model.

[0028] Icons: 100-arc extinguishing chamber; 110-housing; 111-mounting piece; 1111-slot; 1112-protrusion; 1113-locking portion; 1114-arc track; 1114a-first plate surface; 1114b-second plate surface; 120-permanent magnet; 121-chamfered structure; 200-isolating switch; 210-base; 220-contact mechanism; 221-moving contact; 222-static contact. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the present utility model, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the utility model product is usually placed when in use. They are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present utility model.

[0033] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Please refer to Figure 1 In one aspect of an embodiment of the present application, an arc extinguishing chamber 100 is provided, comprising a shell 110 and a permanent magnet 120. The shell 110 is a gas-generating material. The middle portion of the shell 110 has a receiving cavity. The permanent magnet 120 is disposed in the receiving cavity. The setting direction of the permanent magnet 120 forms a preset angle α with the extension direction of the shell 110. When the permanent magnet 120 includes a plurality of permanent magnets, the same polarity ends of the plurality of permanent magnets 120 are disposed in the same direction.

[0035] Specifically, Figure 1 As shown, the arc extinguishing chamber 100 includes a housing 110, the middle of the housing 110 has a receiving cavity capable of accommodating a permanent magnet 120, the receiving cavity is provided with a permanent magnet 120, and the number of the permanent magnet 120 is at least one; when there are multiple permanent magnets 120, the same polarity ends of the multiple permanent magnets 120 are arranged in the same direction, and the multiple permanent magnets 120 are arranged side by side at intervals. Figure 7 As shown, the setting direction of the permanent magnet 120 and the extension direction of the shell 110 form a preset angle α, so that the permanent magnet 120 is tiltedly set in the shell 110; optionally, the value of the angle α is 3° to 20°.

[0036] When the moving contact 221 of the disconnector 200 contacts or separates from the stationary contact 222 , the generated arc can be affected by the Lorentz force of the permanent magnet 120 along the magnetic field direction, and quickly moves to the arc extinguishing port of the arc extinguishing chamber 100 , and is extinguished by the arc extinguishing grid inside it.

[0037] The shell 110 of the arc extinguishing chamber 100 is a gas-generating material, and the gas generated by the shell 110 can lengthen the arc until the arc is extinguished, thereby further improving the arc extinguishing efficiency. By combining magnetic blowing and gas blowing, not only the low cost of the arc extinguishing mechanism is maintained, but also the arc can be quickly extinguished, thereby improving the arc extinguishing efficiency.

[0038] It should be noted that, first, in one possible implementation of the present application, Figure 5 and Figure 6 As shown, the edge of the end face where the N pole or S pole of the permanent magnet 120 is located is provided with a chamfered structure 121 .

[0039] Specifically, a chamfered structure 121 is provided between two adjacent edges of the end face of the permanent magnet 120 , which can be provided on the end face where the N pole of the permanent magnet 120 is located, or on the edge of the end face where the S pole is located, to distinguish the N pole or S pole of the permanent magnet 120 .

[0040] When installing a pair of permanent magnets 120 in the accommodating cavity of the shell 110, in order to avoid reversing the magnetic poles of the two permanent magnets 120, the magnetic poles of the permanent magnets 120 can be identified by setting the chamfer structure 121, thereby avoiding reverse insertion of the magnets and also having an anti-mistake effect.

[0041] Second, the magnetic field direction of the permanent magnet 120 is from the N pole to the S pole, wherein the present application does not impose any restrictions on the specific setting orientation of the N pole and the S pole. The end of the permanent magnet 120 close to the moving contact 221 of the isolating switch 200 can be the N pole or the S pole, but it should be ensured that when the permanent magnet 120 includes multiple permanent magnets, the same polarity ends of the multiple permanent magnets 120 are arranged in the same direction, that is, the ends of the moving contacts 221 of the multiple permanent magnets 120 close to the isolating switch 200 are all N poles or all S poles, so as to ensure that the arc can be subjected to the stable Lorentz force of the permanent magnet 120 along the magnetic field direction, and quickly move to the arc extinguishing port of the arc extinguishing chamber 100.

[0042] Third, please refer to Figure 2 , Figure 3 and Figure 4 In one possible implementation mode of the present application, the shell 110 includes two mounting members 111, a slot 1111 is provided in the middle of the mounting members 111, and the two mounting members 111 are connected so that the two slots 1111 are connected to form a accommodating cavity; the permanent magnet 120 is arranged through the slots 1111 of the two mounting members 111.

[0043] Specifically, please refer to Figure 2 , Figure 3 and Figure 4The housing 110 includes two mounting members 111. Two slots 1111 are arranged side by side at intervals in the middle of the mounting members 111. The slots 1111 of the two mounting members 111 are arranged opposite to each other and the positions thereof are adapted. The ends of the slots 1111 of the two mounting members 111 that are close to each other are connected to the outside. The arrangement of the two detachable mounting members 111 facilitates the disassembly and assembly of the permanent magnet 120 and the replacement of the arc extinguishing chamber 100 and the permanent magnet 120.

[0044] The end faces of the two mounting members 111 are aligned to connect the two mounting members 111, so that the slots 1111 of the two mounting members 111 are interconnected to form a receiving cavity, and the opposite ends of the permanent magnet 120 are respectively inserted into the slots 1111 of the two mounting members 111, so that the permanent magnet 120 is arranged in the mounting members 111 along its extension direction, so that the arc generated when the moving contact 221 and the static contact 222 of the disconnector 200 are in contact or separation can be affected by the Lorentz force of the permanent magnet 120 along the magnetic field direction and quickly move to the arc track 1114, thereby improving the reliability of arc extinguishing.

[0045] For example, Figure 8 As shown, when the permanent magnet 120 includes multiple ones, the central axes of two adjacent permanent magnets 120 along the thickness direction form a preset angle β, so that the multiple permanent magnets 120 are arranged in an arc shape; wherein the thickness direction is perpendicular to the setting direction of the permanent magnet 120; optionally, the angle β is 10° to 30°.

[0046] In one possible implementation of the present application, Figure 2 and Figure 3 As shown, a protruding portion 1112 and a clamping portion 1113 are respectively provided on the sides of the two mounting members 111 that are close to each other. The protruding portion 1112 and the clamping portion 1113 are structurally adapted, and the protruding portion 1112 can be clamped with the clamping portion 1113 .

[0047] Specifically, a protrusion 1112 is provided at the end of one of the mounting members 111 near the other mounting member 111, and correspondingly, a clamping portion 1113 is provided at the end of the other mounting member 111. The protrusion 1112 and the clamping portion 1113 are adapted to each other in structure, so that the protrusion 1112 can be clamped and connected with the clamping portion 1113, thereby realizing the connection between the two mounting members 111. With such a setting, the connection between the two mounting members 111 is more stable, and the assembly and disassembly process of the two mounting members 111 is also more convenient.

[0048] For example, Figure 2 and Figure 3As shown, a first plate surface 1114a is extended from the end surfaces of the two mounting members 111 facing away from each other, and the first plate surface 1114a is perpendicular to the plane where the permanent magnet 120 extends. The first plate surface 1114a is bent at one end away from the mounting member 111 to form a second plate surface 1114b, and the first plate surface 1114a and the second plate surface 1114b form an arc track 1114.

[0049] Specifically, the end surfaces of the two mounting members 111 facing away from each other are extended with a running arc track 1114, such as Figure 2 and Figure 3 As shown, the arc runway 1114 is composed of a first plate surface 1114a and a second plate surface 1114b connected to each other. The first plate surface 1114a is parallel to the end surface of the mounting member 111 and is perpendicular to the plane where the permanent magnet 120 extends. The second plate surface 1114b is arranged on the side of the first plate surface 1114a away from the mounting member 111 and has a certain angle with the first plate surface 1114a. The two second panels are arranged oppositely so that the arc runway 1114 of the two mounting members 111 form a groove structure. The arc generated when the moving contact 221 and the static contact 222 of the disconnector 200 are in contact or separation can be transferred to the arc extinguishing port along the arc runway 1114 and finally extinguished. The arc runway 1114 with a groove structure can carry the arc blown by the magnetic force, accelerate the arc transfer speed, and improve the arc extinguishing effect of the arc extinguishing chamber 100.

[0050] On the other hand of the embodiment of the present application, there is provided an isolating switch 200, including a base 210 and an arc extinguishing chamber 100, the base 210 is provided with a contact mechanism 220, the contact mechanism 220 includes relatively arranged static contacts 222 and a moving contact 221 movably cooperated with the static contact 222, the arc extinguishing chamber 100 is respectively arranged on opposite sides of the contact mechanism 220, and the permanent magnet 120 in the arc extinguishing chamber 100 passes through the plane to which the moving contact 221 and the static contact 222 belong when they are in electrical contact.

[0051] Specifically, please refer to Figure 8 and Fig. 9 , the present application can also provide an isolating switch 200. The isolating switch 200 includes a base 210, on which a contact mechanism 220 is arranged. The contact mechanism 220 includes at least one pair of stationary contacts 222 and a moving contact 221, and the moving contact 221 can move in a direction away from or close to the stationary contact 222 to separate from or contact the stationary contact 222. The isolating switch 200 also includes at least one pair of arc extinguishing chambers 100, which are relatively arranged on both sides of the contact mechanism 220 to be arranged at the contact or disconnection position of the stationary contact 222 and the moving contact 221, and the stationary contact 222 and the moving contact 221 are arranged between two arc tracks 1114 of the arc extinguishing chamber 100. When the moving contact 221 contacts or disconnects with the stationary contact 222, the generated arc can enter the arc extinguishing chamber 100 and be extinguished.

[0052] The permanent magnet 120 in the arc extinguishing chamber 100 penetrates the plane where the moving contact 221 and the static contact 222 are in electrical contact, so that the arc generated when the moving contact 221 and the static contact 222 are in contact or separation can be affected by the Lorentz force of the permanent magnet 120 along the magnetic field direction and quickly move to the arc runway 1114 of the arc extinguishing chamber 100, thereby improving the reliability of arc extinguishing. Among them, the specific structure and beneficial effects of the arc extinguishing chamber 100 have been introduced in detail above and will not be repeated here. The disconnector 200 obtained by the above design can make the arc simultaneously affected by the magnetic blowing effect and the air blowing effect of the arc extinguishing chamber 100, and can make the arc disappear quickly while maintaining low cost, thereby improving the safety and reliability of the disconnector 200.

[0053] It should be noted that if Figure 8 and Fig. 9 As shown, in one possible implementation mode of the present application, the contact mechanism 220 of the disconnector 200 is a translational opening and closing switch; in another possible implementation mode of the present application, the disconnector 200 can also be a rotary opening and closing switch (not shown in the figure). The present application does not impose any restriction on the specific opening and closing mode of the contact mechanism 220 of the disconnector 200. As long as the arc extinguishing chamber 100 is arranged at the contact or disconnection point of the moving contact 221 and the static contact 222 of the contact mechanism 220, and the permanent magnet 120 passes through the plane where the moving contact 221 and the static contact 222 are in electrical contact, it can ensure that the arc is simultaneously subjected to the magnetic blowing effect and the air blowing effect of the arc extinguishing chamber 100, so as to achieve rapid arc extinguishing.

[0054] Optionally, the permanent magnets 120 respectively arranged in two oppositely arranged arc extinguishing chambers 100 are parallel to each other; or, the permanent magnets 120 respectively arranged in two oppositely arranged arc extinguishing chambers 100 are symmetrically arranged with the contact mechanism 220 as the symmetry axis, and the ends close to the moving contact 221 are close to each other; or, the permanent magnets 120 respectively arranged in two oppositely arranged arc extinguishing chambers 100 are symmetrically arranged with the contact mechanism 220 as the symmetry axis, and the ends close to the moving contact 221 are far away from each other.

[0055] Specifically, at least one pair of arc extinguishing chambers 100 are disposed oppositely on both sides of the contact mechanism 220, and the permanent magnets 120 in the two oppositely disposed arc extinguishing chambers 100 are also disposed oppositely. Fig. 9As shown, the permanent magnets 120 respectively arranged in the two oppositely arranged arc extinguishing chambers 100 are parallel to each other. Since the permanent magnets 120 are inserted in the shell 110 of the arc extinguishing chamber 100 at a certain angle, the permanent magnets 120 in the oppositely arranged arc extinguishing chambers 100 are inclined at a certain angle in the same direction; or, the permanent magnets 120 respectively arranged in the two oppositely arranged arc extinguishing chambers 100 are symmetrically arranged with the contact mechanism 220 as the symmetry axis. Since the permanent magnets 120 are inserted in the permanent magnets 120 at a certain angle, the ends of the permanent magnets 120 respectively arranged in the two oppositely arranged arc extinguishing chambers 100 close to the moving contact 221 are close to each other and inclined at a certain angle (not shown in the figure), or the ends close to the moving contact 221 are separated from each other and inclined at a certain angle, as shown in FIG. Fig.10 shown.

[0056] The above description is only an optional embodiment of the utility model and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

[0057] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present utility model will not further describe various possible combinations.

Claims

1. An arc extinguishing chamber, characterized in that: The invention comprises a shell (110) and a permanent magnet (120), wherein the shell (110) is made of a gas-generating material, a central portion of the shell (110) has a receiving cavity, the permanent magnet (120) is arranged in the receiving cavity, and the arrangement direction of the permanent magnet (120) forms a preset angle α with the extension direction of the shell (110); when the permanent magnet (120) comprises a plurality of permanent magnets, the same polarity ends of the plurality of permanent magnets (120) are arranged in the same direction.

2. The arc extinguishing chamber according to claim 1, characterized in that: When the permanent magnets (120) are multiple, the central axes of two adjacent permanent magnets (120) along the thickness direction form a preset angle β, so that the multiple permanent magnets (120) are arranged in an arc shape; wherein the thickness direction is perpendicular to the arrangement direction of the permanent magnets (120).

3. The arc extinguishing chamber according to claim 1, characterized in that: The angle α is in the range of 3° to 20°.

4. The arc extinguishing chamber according to claim 2, characterized in that: The angle β is in the range of 10° to 30°.

5. The arc extinguishing chamber according to claim 1, characterized in that: The housing (110) comprises two mounting members (111), a slot (1111) is provided in the middle of the mounting members (111), and the two mounting members (111) are connected so that the two slots (1111) are connected to form a receiving cavity; the permanent magnet (120) is arranged through the slots (1111) of the two mounting members (111).

6. The arc extinguishing chamber according to claim 5, characterized in that: A first plate surface (1114a) extends from the end surfaces of the two mounting members (111) which face away from each other. The first plate surface (1114a) is perpendicular to the plane where the permanent magnet (120) extends. A second plate surface (1114b) is bent at one end of the first plate surface (1114a) away from the mounting member (111). The first plate surface (1114a) and the second plate surface (1114b) form a running arc track (1114).

7. The arc extinguishing chamber according to claim 5, characterized in that: A protruding portion (1112) and a clamping portion (1113) are respectively provided on the sides of the two mounting parts (111) close to each other. The protruding portion (1112) is structurally compatible with the clamping portion (1113), and the protruding portion (1112) can be clamped with the clamping portion (1113).

8. The arc extinguishing chamber according to claim 1, characterized in that: The edge of the end face where the N pole or the S pole of the permanent magnet (120) is located is provided with a chamfered structure (121).

9. An isolating switch, characterized in that: It comprises a base (210) and an arc extinguishing chamber (100) as claimed in any one of claims 1 to 8, wherein a contact mechanism (220) is provided on the base (210), wherein the contact mechanism (220) comprises relatively arranged static contacts (222) and a moving contact (221) movably matched with the static contact (222), arc extinguishing chambers (100) are respectively provided on opposite sides of the contact mechanism (220), and a permanent magnet (120) in the arc extinguishing chamber (100) penetrates the plane to which the moving contact (221) and the static contact (222) belong when they are in electrical contact.

10. The isolating switch according to claim 9, characterized in that: The permanent magnets (120) respectively arranged in the two oppositely arranged arc extinguishing chambers (100) are parallel to each other; or, the permanent magnets (120) respectively arranged in the two oppositely arranged arc extinguishing chambers (100) are symmetrically arranged with the contact mechanism (220) as a symmetry axis, and the ends close to the moving contact (221) are close to each other; or, the permanent magnets (120) respectively arranged in the two oppositely arranged arc extinguishing chambers (100) are symmetrically arranged with the contact mechanism (220) as a symmetry axis, and the ends close to the moving contact (221) are far away from each other.

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